Bitumen modification by polymer is known in literature to produce polymer modified bitumen with enhanced rheological properties but production of all grades of polymer modified bitumen from petroleum vacuum residue is neither feasible nor cost effective.
Crumb rubber modification has been proven to enhance the properties of pure bitumen but crumb rubber modified bitumen has inherent issue of storage stability causing difficulty in transportation. There are two general methods for incorporating crumb rubber in asphalt. One is called dry method, where crumb rubber is directly incorporated in bituminous mixture. Another method is called wet method, where the crumb rubber is first incorporated in the asphalt and then in to the bituminous mixture.
Following wet method, several compositions have been developed in prior art for incorporation of crumb rubber in asphalt along with polymer to enhance storage stability and rheological properties of asphalt. European Patent EP0305225 discloses a manufacturing method which improves the stability of a composition: bitumen, crumb rubber, aromatic oil and elastomer as catalyst of said process, from 6 hours to ten days.
EP 2315803A1 discloses a bitumen composition comprising crumb rubber, a polymer comprising glycidyl functional groups and wax. U.S. Pat. No. 7,446,139 B2 discloses the modified asphalt binders comprising neat asphalt, crumb rubber, one or more synthetic polymers and one or more acid. EP 2055745 discloses the composition comprising bitumen, crumb rubber, a polymer which can be vulcanized and vulcanizing agent. WO 9927018 also discloses compositions wherein polymers of various types are used to improve the stability to storage of the bitumen crumb rubber.
The existing prior arts have not disclosed on the production of hybrid bitumen from vacuum. The present invention discloses production of hybrid bitumen from vacuum residue using dual functional agent which may react with crumb rubber leading to enhance storage stability of hybrid modified bitumen in one aspect and in another way it increase the hardening of bitumen which further improves the rheological properties of asphalt effectively.